How materials are cycled in an ecosystem

• Sampling allows us to measure the abundance and distribution of species in an ecosystem
• Atoms exist in different forms or compounds at different times in history and cycle between them
• Carbon and water can exist in different forms at different times
• Feeding relationships between organisms in an ecosystem can be seen in food chains
• Rocks can cycle between igneous, sedimentary, and metamorphic forms
• Humans eat protein in the form of meat from other animals, which is broken down into amino acids for growth and repair
• When humans die, the building blocks are returned to the environment for use by other organisms
• Decomposing bacteria and fungi help break down dead organisms, recycling minerals and nutrients in the environment
• Decomposers also respire and release carbon dioxide to the environment, contributing to the carbon cycle